A challenge for the minimally invasive exploration and treatment of internal areas of the human anatomy continues to be adequately visualizing the area of concern. Visualization can be especially troublesome in minimally invasive procedures in which small diameter, flexible and elongate instruments, such as catheters, endoscopes, or more specifically, ureteroscopes and duodenoscopes (herein, all are classified as surgical scopes), are navigated through natural passageways of a patient to an area of concern, either in the passageway or in an organ accessible through the passageway.
A common example is flexible ureteroscopy. Ureteroscopy involves procedures that are used to diagnosis and treat urinary tract diseases such as urinary calculi and ureteral strictures. An ureteroscope is inserted through urethral opening and threaded along the urinary tract, into the bladder, through the ureteral opening and into the kidney calyx. Diagnosis and/or treatment occur under direct visualization as classically provided by fiber optic coupled to imaging systems and light sources. Tiny cameras and light emitting diodes (LEDs) have been exploited in modern ureteroscope design. FIG. 1 depicts a modern ureteroscope tip.
Ureteroscopes are typically 3 mm to 4 mm (10 Fr. to 13 Fr.) in diameter 5 and include a sheath (not shown, coupled to a step on tip outer diameter 65) that encapsulates a fiber optic element (imaging bundle) or imaging chip 15/20 (sensor/substrate) and wiring 55, a fiber optic illumination element (illumination bundle) or LED 30/35 (sensor/substrate) and wiring 50 and a working channel 60. Wires are connected via contacts 40/45 (LED/sensor) located upon the substrate 35/20 (LED/sensor). Windows 10/25 (sensor/LED) typically seal the chips from exposure to surgical irrigants.
The working channel (aka “forceps channel”) 60 is a lumen for instrument access to tissue through the distal tip of the scope, permitting passage of devices, such as guidewires, optical fibers for delivery of laser energy and stone retrieval baskets. The working channel 60 is also used for introducing sterile irrigant. Drainage of irrigant and surgical detritus typically occurs about the outer diameter of the scope, usually housed within an “access sheathe”. Irrigation flow is partially occluded by instruments within the working channel 60, and inadequate flow may allow surgical detritus to build up and impair visualization during surgery. Larger working channels are preferred for both permitting larger instruments to be employed in surgery and for maintenance of a clear surgical field. For reference, in the prior art tip illustrated in FIG. 1, the total tip diameter is 3.2 mm and the working channel is 1.1 mm.
Illumination is typically provided via an optical fiber bundle, terminated within the distal tip of the scope, transmitting light from a source outside of the body. Quite recently, LEDs 30/35 have been used to replace the fiber bundle. Visualization is afforded via an imaging optical fiber bundle or, beginning roughly 20-years ago, via a camera chip 15/20 (sensor/substrate) at the distal tip. Most ureteroscopes also incorporate a steering mechanism (not shown), which allows the distal tip of the scope to be deflected in one or more planes to follow the natural lumen with minimal trauma.
Size is of primary importance for minimally invasive imaging and access devices. Larger diameter devices are typically less flexible (less “steerable”), cannot pass smaller lumen (e.g. in pediatrics) and induce more trauma than smaller devices while themselves suffering damage in forced passage. Larger devices do offer competing advantages, such as permitting larger working channels that provide better irrigant flow and access for larger instruments, but smaller, more flexible devices are clearly favored.
Another compromise made in prior art imaging scopes is the amount and quality of the lighting provided. Fiber optic bundles for lighting are kept small in total diameter and use very small core optical fibers, uncoated, to minimize ureteroscope stiffness and overall diameter; a single fiber bundle or LED 30/35 is typically used and is positioned to one side of the imaging element, providing uneven illumination of the visual field, particularly where that filed is complex in topography.
It would be useful to provide a small diameter, flexible ureteroscope or duodenoscope or similar device that provides superior illumination and visualization within as compact a package as possible.